[3/3] newlib/libm/math: Make pow/powf return qnan for snan arg

Message ID 20200326001821.174426-4-keithp@keithp.com
State Accepted
Commit 6295d759133c399f1d4fcd224fa4f1bd2794288b
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Series
  • [1/3] newlib/libm/common: Fix modf/modff returning snan
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Commit Message

Keith Packard via Newlib March 26, 2020, 12:18 a.m.
The IEEE spec for pow only has special case for x**0 and 1**y when x/y
are quiet NaN. For signaling NaN, the general case applies and these functions
should signal the invalid exception and return a quiet NaN.

Signed-off-by: Keith Packard <keithp@keithp.com>

---
 newlib/libm/math/e_pow.c  | 13 +++++++++----
 newlib/libm/math/ef_pow.c | 10 +++++++---
 2 files changed, 16 insertions(+), 7 deletions(-)

-- 
2.25.1

Patch

diff --git a/newlib/libm/math/e_pow.c b/newlib/libm/math/e_pow.c
index 5fd28e65f..4c450ec05 100644
--- a/newlib/libm/math/e_pow.c
+++ b/newlib/libm/math/e_pow.c
@@ -58,6 +58,8 @@ 
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
+
 #if __OBSOLETE_MATH
 
 #ifndef _DOUBLE_IS_32BITS
@@ -116,14 +118,17 @@  ivln2_l  =  1.92596299112661746887e-08; /* 0x3E54AE0B, 0xF85DDF44 =1/ln2 tail*/
 	EXTRACT_WORDS(hy,ly,y);
 	ix = hx&0x7fffffff;  iy = hy&0x7fffffff;
 
-    /* y==zero: x**0 = 1 */
-	if((iy|ly)==0) return one; 	
+    /* y==zero: x**0 = 1 unless x is snan */
+	if((iy|ly)==0) {
+	    if (issignaling_inline(x)) return x + y;
+	    return one;
+	}
 
     /* x|y==NaN return NaN unless x==1 then return 1 */
 	if(ix > 0x7ff00000 || ((ix==0x7ff00000)&&(lx!=0)) ||
 	   iy > 0x7ff00000 || ((iy==0x7ff00000)&&(ly!=0))) {
-	    if(((hx-0x3ff00000)|lx)==0) return one;
-	    else return nan("");	
+	    if(((hx-0x3ff00000)|lx)==0 && !issignaling_inline(y)) return one;
+	    else return x + y;
 	}
 
     /* determine if y is an odd int when x < 0
diff --git a/newlib/libm/math/ef_pow.c b/newlib/libm/math/ef_pow.c
index d9e85a95e..d4ea4c5e8 100644
--- a/newlib/libm/math/ef_pow.c
+++ b/newlib/libm/math/ef_pow.c
@@ -14,6 +14,7 @@ 
  */
 
 #include "fdlibm.h"
+#include "math_config.h"
 
 #if __OBSOLETE_MATH
 #ifdef __v810__
@@ -74,13 +75,16 @@  ivln2_l  =  7.0526075433e-06; /* 0x36eca570 =1/ln2 tail*/
 	ix = hx&0x7fffffff;  iy = hy&0x7fffffff;
 
     /* y==zero: x**0 = 1 */
-	if(FLT_UWORD_IS_ZERO(iy)) return one; 	
+	if(FLT_UWORD_IS_ZERO(iy)) {
+	    if (issignalingf_inline(x)) return x + y;
+	    return one;
+	}
 
     /* x|y==NaN return NaN unless x==1 then return 1 */
 	if(FLT_UWORD_IS_NAN(ix) ||
 	   FLT_UWORD_IS_NAN(iy)) {
-	    if(hx==0x3f800000) return one;
-	    else return nanf("");
+	    if(hx==0x3f800000 && !issignalingf_inline(y)) return one;
+	    else return x + y;
 	}
 
     /* determine if y is an odd int when x < 0